In a method and system for controlling a direct current to direct current (DC-DC) converter includes an inductor coupled to receive a voltage input at an input terminal. A diode is coupled in series between the inductor and an output terminal of the DC-DC converter. A switch is coupled between the inductor and a ground reference. The switch receives a control signal from a controller for adjusting a duty cycle of the DC-DC converter. The duty cycle controls an output voltage at the output terminal. The controller generates the control signal in response to receiving a feedback signal, which is derived as a predefined function of a voltage feedback signal indicative of the output voltage and a current feedback signal indicative of a current flowing through the inductor.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A self-oscillating direct current to direct current (DC-DC) converter comprising: an inductor coupled to receive a voltage input at an input terminal; a switch coupled between the inductor and a reference, wherein the switch receives a control signal for adjusting a duty cycle to control output voltage at an output terminal; and a controller coupled to receive a feedback signal derived as a predefined function of a voltage feedback signal indicative of the output voltage and a current feedback signal indicative of a current flowing through the inductor, wherein the controller provides the control signal in response only to the feedback signal, the controller imposing constraints on the control signal consisting essentially of or more of applying the control signal for a minimum off time when a load coupled between the output terminal and the reference draws a load current above a first threshold, applying the control signal for a minimum on time when a load coupled between the output terminal and the reference draws a load current below a second threshold, applying the control signal for a maximum on time when a load coupled between the output terminal and the reference draws a load current above a current threshold and when the voltage input is below a voltage threshold.
2. The converter of claim 1 , wherein the controller asserts the control signal to close the switch when the feedback signal is deasserted and the controller deasserts the control signal to open the switch when the feedback signal is asserted.
3. The converter of claim 1 , wherein the current feedback signal is generated by a current feedback circuit coupled between the output terminal and the reference, wherein the current feedback circuit provides the current feedback signal in response to adding a first component indicative of the output voltage to a second component indicative of the current flowing through the inductor.
4. The converter of claim 3 , wherein the voltage feedback signal is generated by an integrator, wherein the integrator provides the voltage feedback signal by integrating a second voltage feedback signal and a voltage reference signal and wherein the integrator compensates for a direct current (DC) voltage offset caused by the second component.
5. The converter of claim 4 , wherein the second voltage feedback signal is generated by a voltage feedback circuit coupled between the output terminal and the reference, wherein the voltage feedback circuit provides the second voltage feedback signal indicative of the output voltage.
6. The converter of claim 4 , wherein the DC voltage offset by an injection current flowing through a sense resistor during an on time of the switch, wherein the injection current is proportional to the current flowing through the inductor.
7. The converter of claim 1 , wherein the predefined function is a comparator, wherein the comparator asserts the feedback signal when the current feedback signal is greater than the voltage feedback signal and wherein the comparator deasserts the feedback signal when the current feedback signal is not greater than the voltage feedback signal.
8. The converter of claim 1 , wherein the controller switches the switch at a variable switching frequency without receiving a clock signal.
9. The converter of claim 8 , wherein the variable switching frequency is limited by a minimum on time and a minimum off time of the switch.
10. The converter of claim 9 , wherein the minimum on time and the minimum off time of the switch filter out a noise component of the feedback signal.
11. The converter of claim 1 , wherein a diode is coupled in series between the inductor and the output terminal, wherein a load is coupled between the output terminal and the reference, wherein the load is an integrated circuit chip.
12. A method of controlling a self-oscillating direct current to direct current (DC-DC) converter, the method comprising: receiving a current feedback signal indicative of a current flowing through an inductor of the DC-DC converter; receiving a voltage feedback signal indicative of an output voltage of the DC-DC converter; comparing the current feedback signal and the voltage feedback signal to provide a feedback signal; and generating a control signal to control a duty cycle of the DC-DC converter responsive only to the feedback signal, wherein the duty cycle regulates the output voltage, the controller imposing constraints on the control signal consisting essentially of applying the control signal for a minimum off time when a load coupled to the output voltage draws a current above a first threshold, applying the control signal for a minimum on time when the load draws the load current below a second threshold, applying the control signal for a maximum on time when the load draws the laooad current above a current threshold and when an input voltage is below a voltage threshold.
13. In the method of claim 12 , wherein the output voltage is provided to a load coupled to the DC-DC converter, wherein the load is an integrated circuit chip.
14. In the method of claim 12 , wherein the DC-DC converter is one of a boost converter, a buck converter, a buck-boost converter, and a Cuk converter or a combination thereof.
15. An electronic system comprising: a load coupled to an output terminal; and a self-oscillating direct current to direct current (DC-DC) converter operable to provide power to the load, the converter including: an inductor coupled to receive a voltage input at an input terminal; a switch coupled in series between the inductor and a reference, wherein the switch receives a control signal for adjusting a duty cycle to control an output voltage at the output terminal; and a controller coupled to receive a feedback signal derived only as a predefined function of a voltage feedback signal indicative of the output voltage and a current feedback signal indicative of a current flowing through the inductor, wherein the controller provides the control signal in response to the feedback signal, the controller imposing constraints on the control signal consisting essentially of applying the control signal for a minimum off time when the load draws a load current above a first threshold, applying the control signal for a minimum on time when the load draws the load current below a second threshold, applying the control signal for a maximum on time when the load draws the load current above a current threshold and when the voltage input is below a voltage threshold.
16. The system of claim 15 , wherein the load is a digital signal processor (DSP).
17. The system of claim 15 , wherein the DC-DC converter is one of a boost converter, a buck converter, a buck-boost converter, and a Cuk converter or a combination thereof.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
May 18, 2005
June 24, 2008
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.